Venetian blind and slat therefor



July 30, 1940. H. J. SCHMITZ VENETIAN BLIND AND SLAT THEREFOR Filed March 1, 1939 ATTORNEY.

Patented July 30, 1940 UNITED STATES PAT NTQLOFF ICE VENETIAN BLIND AND SLAT THEREFOR Herbert J. Schmitz, Kenilworth, Ill., assignor to Chicago Venetian Blind Company, Chicago, Ill., a corporation of Illinois Application March 1,

v 9 Claims.

This invention relates to Venetian blinds and more particularly to slats therefor made of metal orsimilar sheet material.

There have been various proposals for metal slats, some before and some since the present invention was placed on the market. One of the problems is to provide adequate strength without making the slats too heavy. To this end various curved, angular or beaded configurations have been proposed, but the. shapes have been subject to various objections or have failed to utilize fully the advantages-obtainable from metal slats. One common fault has been in making the slats nonsymmetrical with one edge turned up and the other turned down, with the result that the slats would not nest vertically as they were drawn up by the raising cords but instead each slat would be displaced laterally with respect to the one below it. Another fault has been in so shaping the slats that they would not nest closely together as in the case of corrugated slats having closely spaced ribs or slats in which the edges are provided with a closed or nearly closed head. Others, while avoiding these last named difliculties, were insufliciently rigid.

According to the present invention a shape is providedwhich satisfies the conflicting considerations. A gentle transverse curvature of the slat, together with the provision of narrow flanges bent sharply from its edges, provides adequate strength. The inclination of the flanges at a very wide angle with respect to one another, because of bending them in a reverse direction from the curvature, enables the slats to nest closely together in spite of the flanges which give them rigidity. The symmetrical shape of the slat causes it to nest evenly without offsetting successive slats from one another.

In addition, a slat of this invention makes excellent use of the potentialities of metal. The lustrous finish and the slight curvature of the slats causes the maximum transmission of light through the blind when the blind is open, although the curvature diffuses the light in a highly desirable manner. The thinness of the slats together with their shape permits the maximum flow of air thorugh the blind when it is open, and a surprisingly great flow of air even when it is turned to a position that will shut out a great majority of the light. Although the metallic luster of the blind and the shape of the slats cause a maximum amount of light to pass through the blind when it is open, they also act as a very good repellent of light when it is closed. The blind will not only shut out most of the out- 1939, Serial No. 259,241

door light when desired, but it will also reflect rather than absorb a very high percentage of the indoor light, and thus conserve artificial illumination. A fairly high reflectivity is not objectionable from the standpoint of glare, however, because the shape of the slat diffuses the light. Likewise, the smooth metallic finish of the blind renders cleaning exceptionally easy, and in fact it is less likely to catch the dirt than a blind with relatively rough-surfaced, painted wooden slats.

Additional advantages and objects of the invention will be apparent from the following description and from the drawing, in which:

Fig. l is a perspective view of one form of the slat chosen for illustration of this invention.

Fig. 2 is a fragmentary sectional view showing three slats such as that of Fig. 1 embodied in a Venetian blind, the figure illustrating particularly the high degree of light transmission through the blind.

Fig. 3 is a similar view with the slats turned to a position at which they will expel most of the light.

Fig. 4 is a similar view showing the slats arranged in a position which will admit a very high percentage of the light but thoroughly diffuse it.

Fig. 5 is a view showing the blind closed with its concave side inward, showing the high degree of diffusion of the artificial light striking the inside of the blind and the absence of loss by passage of the light through the blind.

Fig. 6 is a similar view showing a high degree of downward diffusion of the light by the slats when the slats are turned with their convex.

sides inwardly.

Fig. 7 is a fragmentary view showing the neat and compact manner in which the slats nest together as the blind is raised, the shape of the slats automatically centeringthem with respect to one another.

Fig. 8 is a cross-sectional view of a modified form of slat.

Two embodiments of the invention have been chosen for illustration and description, in compliance with section 4888 of the Revised Statutes, but persons skilled in the art will readily perceive other means for accomplishing the same results, and the claims are therefore to be construed as broadly as possible, consistent with the prior art.

As seen in Fig. 1, a preferred form of the slat H is an elongated specially shaped strip of metal. The cross-sectional shape of the slat is seen best in Fig. 2. The major portion of the cross section comprises a single gradual curvature from 12 to ii. In addition, there is a strengthening flange l3 along ,each edge of the slat, these flanges being formed by a reverse curvature at ll, which curvature is preferably so sharp as to be substantially angular. Although the flanges II are very narrow, the slat is very much more rigid with these flanges than it would be without them.

The slats may be supported by ladder tapes in the usual way. The ladder tapes customarily include side tapes IG, which may also be called tilt tapes, and cross webs H on which the slats rest. As is well known, the cross webs l1 space the slats the desired distance apart, and the manipulation of the tilt tapes it shifts the slats from one position to another.

If it is desired to get the maximum of direct light from the sun or from the sky, the slats may -be tilted to a position such as that shown in Fig.

2. As seen in this position, the light indicated by the various arrows will for the most part pass between the slats unaffected by them. For convenience the lines of arrows will be called rays since they represent rays of light. As will be seen from Fig. 2, even the rays which strike the slats will for the most part be reflected into the room. Thus, the ray A approaching from the upper sky strikes the underside of the middle slat and is reflected by it to the upper side of the lower slat by which it is reflected into the room. Likewise, the horizontal rays B, which are not usually nearly so intense and which strike the underside of the middle slat except near the upper edge thereof, will be reflected into the room.

The slats are not only made of metal but preferably have a substantially transparent or metallic finish. Aluminum slats having a largely transparent oxide coating is highly desirable, although the slat is preferably treated to make it slightly duller than the brilliantly reflective metal could be, the duller appearance being generally considered more pleasing to the eye and decreasing the likelihood of excessive glare. Of course, other metal coated with a transparent film of varnish or other preservative could be used. The term highly reflective surface may be used to include surfaces having such substantially transparent films or coatings thereon as well as a truly metallic surface.

It is often desired to exclude the great majority of the light from the room. This can be accomplished very efiectively with the slats of the present invention by turning the slats to the position shown in Fig. 3. From this it is seen that both the rays A and B are reflected in such a direction that they do not pass into the room. Of course, due to the dulled surfacing of the slats there will be some diffusion and a smal percentage of the light from these rays will find its way into the room to provide a very soft light, supplemented by the small amount of light which is reflected from the ground upwardly at a rather steep angle so that it may pass between the slats. It will be understood that in commercial blinds the slats do not close tightly against one another and hence cannot shut out the light completely. As a matter of fact, it is desirable for them to have a fairly wide spacing so that a plentiful supply of air can'pass between the slats for ventilation. It may be mentioned in this connection that one advantage of the metal slats is that because of their thinness they permit more air to pass between them.

Probably the most common adjustment for blinds, except the closed position of Fig. 3, is a position approximately that of Fig. 4 intended to diffuse the direct rays of light from the sun or short, practically all of the light which strikes the blind, except that striking the narrow flanges I3, will be reflected into the room so far as the angles of reflection are concerned. Of course, some of the light will be absorbed rather than reflected because of the incomplete reflecting powers of the slats. In this connection it should be noted that the rays E and F, which are reflected upwardly into the room, will be brighter than the rays C and D, which are refiectedtwice and pass downwardly into the room. This is desirable since the rays E and F will normally strike the ceiling or upper walls of the room, and for good lighting it is desirable to have the ceiling and upper walls lighted more intensely than the lower part of the room.

Figs. 5 and 6 show the conserving efiect of the slats with respect to artificial illumination on the inside of the room. As clearly seen from Fig. 5, substantially none of the artificial illumination will pass out through the blind, all of that striking the blind being diffusely reflected. Thus, a ray G approaching from the angle shown will be reflected downwardly at a rather steep angle, while a ray H approaching at the same angle will be reflected only slightly downwardly, and rays I and J approaching from the same angle will be reflected upwardly at successively steeper angles. The only light which will pass through the blind will bethe low intensity light passing rather steeply upwardly, as from the floor.

With the slats turned in the opposite direction; as shown in Fig. 6, a great deal more light would probably pass out through the slats from the upper and more brilliantly lighted portion of the room, but this position of the slats has some advantage in throwing substantially all of the light which strikes them downwardly, as shown by rays K, L and M. With artificial lighting the rays which pass downwardly from the blind are more likely to be useful than those which pass upward- Besides the light transmitting, diffusing and obstructing qualities of the illustrated slats, there are other very important advantages illustrated by Fig. 7. These advantages are in connection with the nesting of the slats as the blind is raised by a raising cord 21 which commonly extends downwardly through slots in the slats to a bottom rail 22. When the cord 2| is raised, it raises the bottom rail 22 which successively picks up the slats so that the slats rest on the bottom rail 22 instead of being supported in spaced relationship by their cross webs I]. As seen from Fig. 7, the slats nest into one another perfectly so that the stack is both compact and straight. Each slat has a centering action on the adjacent slats. This centering action follows from the symmetry of the slats, whereas if they were unsymmetrical, as if one of the flanges turned upwardly and the other downwardly, each slat would tend to displace the one above it slightly from the center and" the stack would tend to lean in one direction or the other.

In connection with the compactness of the stack, it should be noted that the slats themselves are quite thin, being made of metal, and that their effective thinness is substantially only the thickness of the metal since the flanges are so shaped that the slats will nest one within the other and will not be separated from one another by the flanges. As a result of the fact that the slats have an effective thinness much thinner than conventional wooden slats, a blind made of these slats can be drawn up so that it takes up on y about half of the room which would be required for a similar blind of conventional wooden slats. There would be a further reduction of space if it were not for the fact that the connecting portions of the tilt tape do not all fold away from the slats as shown at 28 but alternately fold in between the slats as shown at 21. Of course, this folding of the tapes is the same with wooden slats. Except for the space which the tape requires within the slat, the improvement of the metal slats over the wooden slats would probably be even more noticeable. By way of example, it may be noted that a blind having about 35 metal slats could be drawn up so that its slats and the cross webs of the ladder tape occupy less than an inch and a half were it not for the side tapes, while about two and a half inches are required with the side tapes folded in as they naturally fold. By contrast, a blind with wooden slats has been measuredv and found to require about six and a half inches for 35 slats.

From the foregoing it is evident that a slat has been provided which gives maximum light transmission, maximum outside light exclusion, maximum inside light conservation, and excellent light diffusion, when each of these is desired, while at the same time giving excellent air passage through the blind and stacking up much more compactly than conventional wooden slats or other metal slats of comparable rigidity, the stack also being exceptionally neat because of the selfcentering effect of the slats.

It should be recognized that many of these advantages can be obtained with other shapes than that illustrated. For example, the single transverse curvature could be broken up into two similar curvatures separated by an angle or reverse curve 3|, as illustrated in Fig. 8. The result of such a slat would be very similar. Of course, the light would be reflected or diffused slightly diiferently. Nevertheless, theslat has the advantages of the upwardly concave shape along both its inner and outer edges. As shown in Fig.2, the upwardly (or outwardly) concave shape at the upper edge tends to'exclude the horizontal rays B when' desired, while, as shown in Fig. 4, the upwardly concave shape along the outer edge tends to throw the light of ray F inwardly when desired. Likewise, with either of the forms illustrated many of the advantages may be obtained by assembling the slats in the blind with the convex sides up, although both the diffusion and the appearance of the blind in the various positions will be different.

I claim:

1. A blind including a plurality of elongated slats supported by means extending between them, formed of a thin flexible material and shaped with a single major curvature transversely of the slat and narrow flanges along the sides bent backwardly from the direction of curvature but inclined even at their steepest portions at a wide angle with respect to one another.

2. A blind including a plurality of elongated slats supported by means extending between them, formed of a thin flexible material and shaped with a gentle upwardly concave curvature along both sides of the slat and narrow flanges along the sides bent backwardly from the direction of curvature but inclined even at their steepest portions at a wide angle with respect to one another.

3. A blind including a plurality of elongated slats supported by means extending between them, formed of a. thin flexible material and shaped with a gentle curvature along both sides of the slat concave on the same face of the slat and narrow flanges along the sides bent backwardly from the direction of curvature but inclined even at their steepest portions at a wide angle with respect to one another.

4. An elongated slat formed of thin flexible material and having a single major transverse curvature extending the major portion of the width of the slat and relatively narrow edge flanges bent backwardly with respect to the main curvature adjacent thereto but slanting widely with respect to each other even at their steepest portions.

-5. A blind including a plurality of elongated slats supported by means extending between them, formed of a thin flexible material and shaped with a single major curvature transversely of the slat and narrow flanges bent backwardly from the direction of curvature but inclined even at their steepest portions at a wide angle with respect to one another, said slat having a smooth lustrous surface whereby the reflection of light therefrom may becontrolled to a high degree.

6. A blind including a plurality of elongated slats supported by means extending between them, formed of a thin flexible material and shaped with a gentle upwardly concave curvature along both sides of the slat and narrow flanges along the sides bent backwardly from the direction of curvature but inclined even at their steepest portions at a wideangle with respect to one another, said slat having a smooth lustrous surface whereby the reflection of light therefrom may be controlled to a high degree.

7. An elongated slat formed of thin flexible material and shaped throughout most of its width with a gentle curvature and having relatively narrow edge flanges bent angularly therefrom and backwardly with respect to the main curvature adjacent thereto but slanting widely with respect to each other even at their steepest portions.

8. An elongated slat formed of thin flexible material and shaped throughout most of its width with a gentle curvature and having relatively narrow edge flanges bent angularly therefrom curvature adjacent thereto but slanting widely with respect to each other even at their steepest portions.

HERBERT J. scHMi'rz. 

